In recent years, in order to make a disease and symptom analysis of chronic obstructive pulmonary diseases (COPD), emphysema, and trachea and bronchus diseases, it is required to have a positional registration on the images of a plurality of tree-like constructions obtained at different time phases of three-dimensional (3D) trachea and bronchus images. However, as respiration is a process of dynamic movement, there will be errors in data processing and analysis due to the dynamic movement.
Japanese Patent Publication No. 2014-108208 discloses an image processing method for heart, by which the processing time and the analytical error based on heartbeats can be reduced. In this technical solution, medical images of the heart region at a plurality of time phases are extracted, and, based on the medical images of the heart region at the plurality of time phases, medical images of the heart region at other time phases are interpolated. Accordingly, there is no need to take the medical images at all time phases as has been done previously, resulting in reduced time for shooting and data processing. Moreover, calculating a central line structure of an artery at other time phases by selecting the time phase, where the heart has almost no movement, as a benchmark time phase removes the errors appearing in the images due to the heart movement.
However, in Japanese Patent Publication No. 2014-108208, the selected cardiac regions at the plurality of time phases, where the heart has almost no movement, includes the cardiac region where the heart is in the end-systolic period; when the cardiac region in the end systolic period is selected, while the extraction of the central line of the artery is hardly influenced, the detection precision thereof becomes lower for the extraction of the central line of tiny vessels, such as capillary vessels, since the capillary vessels in the end-systolic period become finer than the capillary vessels in other periods. As a result, in the case of calculating the cardiac region at other time phases based on the heart region in the end-systolic period, there is likely to be a phenomenon that the vein of capillary vessels is lost. That is, the image processing method in Japanese Patent Publication No. 2014-108208 does not apply to the extraction of tiny tubular structures.
In the observation of the lung region, the operator sometimes desires to merely observe the morphologies of the trachea itself at individual time phases. However, in previous techniques, the images of the trachea extracted during the respiratory cycle, besides containing its own variations, further contains the positional movement brought about by the lung movement. That is, in previous techniques, the 3D images of the lung region at individual time phases are obtained by taking images of this region, and then the central lines of the tree-like structure (i.e. trachea and bronchus) at individual time phases are extracted based on the obtained 3D images. With previous techniques, however, the changes of the airway position caused by the contraction and expansion of the lung are mixed together with the changes of the contraction and expansion of the airway itself in respiratory movements, and the actual amount of change of the airway contains not only the motion amount of itself but also the changes in position produced as the lung moves; thus there is a situation where the states of change of the airway itself cannot be precisely reflected when directly extracting the airway at individual time phases. Thus, it is desirable to remove the change in position of the airway due to the contraction and expansion of the lung.
Moreover, in the observation of the lung region, the operator sometimes desires to extract the tinier tube portions, such as the end of the bronchus and so on; however, with the solution of prior art, it is unable to precisely extract the tiny tube portions. Thus, an approach that can precisely extract the entire tube portion is desirable. More specifically, it is desirable to be able to precisely detect the changes in spatial position of the airway itself at individual time phases and to completely reproduce the entire airway including the tiny pipeline ends.
Embodiments described herein are intended to provide a medical image processing apparatus and a medical image processing method that can precisely reproduce the line structures of the bronchus at individual time phases.
The medical image processing apparatus of the embodiments includes obtaining circuitry, calculating circuitry, and transforming circuitry. The obtaining circuitry takes an expiration time phase or an inspiration time phase as a benchmark time phase, and obtains a benchmark line structure, which is a line structure of the bronchus in the lung field, from a medical image at the benchmark time phase. The calculating circuitry calculates a motion amount between a component depicted in the medical image at the benchmark time phase and the component depicted in the medical image at at least one other time phase than the benchmark time phase. The transforming circuitry transforms the benchmark line structure based on the motion amount to obtain an estimated line structure, which is estimated as a line structure at the at least one other time phase.